Field of the Invention
This invention relates generally to perpendicular magnetic recording systems, and more particularly to perpendicular magnetic recording write heads for use in magnetic recording disk drives.
Description of the Related Art
In a perpendicular magnetic recording system like a magnetic recording hard disk drive, the recorded bits are stored in a perpendicular or out-of-plane orientation in the recording layer. The recording or write head in perpendicular magnetic recording disk drives includes a write pole comprising a shaped pole and a main pole for writing to the recording layer, and one or more return poles for return of magnetic flux from the recording layer.
The main pole is typically formed by electroplating a high moment magnetic material, the most common example being iron-cobalt (FeCo) alloys. The main pole is typically surrounded by side shields, a trailing shield and a leading shield but separated from the shields by nonmagnetic gap layers. To form the main pole, in one technique referred to as the Damascene process, a generally trapezoidal shaped trench with outwardly sloped sidewalls is formed in a substrate. A metallic material like Ru is deposited in the trench to serve as the bottom leading gap layer and side gap layers for the main pole. The main pole may be electroplated onto a pole seed layer, such as a NiCr/FeCo bilayer, which is known to produce the soft magnetic property (low coercivity) desirable for the subsequently electroplated FeCo main pole; or by directly plating onto the metallic gap if the main pole magnetic properties are acceptable.
As the data track density increases in disk drives it is desirable to decrease the thickness of the side gap layers. However, current processes to decrease the side gap layer thickness also reduce the thickness of the leading gap layer, which can lead to an undesirable increase in the shunting of magnetic flux through the leading gap layer to the leading shield.
What is needed is a method for making a perpendicular magnetic recording write head with a main pole that has thin side gap layers and a substantially thicker bottom leading gap layer.